This application claims priority to Korean Patent Application No. 2004-102363, filed on Dec. 7, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates generally to optical image sensors, and more particularly, to an active pixel sensor with photo diodes arranged in a honeycomb structure.
2. Description of the Related Art
Imaging systems implemented with complementary metal-oxide semiconductor (CMOS) technology have reduced cost and power compared to conventional charge-coupled device (CCD) imagers. To generate video or still images, various techniques replacing CCD sensors have been developed. Such various techniques are largely divided into passive pixel sensors and active pixel sensors according to whether signal amplification is performed in each pixel or in a support circuit. Passive pixel sensors have advantages of a simple pixel and a high optical fill factor. Active pixel sensors include an amplifier in each pixel to enhance signal transmission and signal sensitivity and thus have a low optical fill factor.
FIG. 1 illustrates a conventional active pixel sensor. A pixel 100 includes a photo diode 101, a transmission transistor 102, a floating diffusion (FD) region, a reset transistor 103, an amplifying transistor 104, and a row selection transistor 105. Since these many elements are included in the pixel 100, a fill factor is low.
Therefore, a pixel architecture with increased fill factor is desired for an active pixel sensor.